Dual audio xvid won't play in standalone dvd player

[XVID Warrior]

Hello y'all. I've been using avidemux intensively the last few weeks and came to learn a lot. I managed to solve any problem googling till now, so i decided to join the forum.

I have an old dvd player with divx support. It plays dual audio in avis i've downloaded pre-muxed. But with the multi streams i remux in avidemux it says "unsupported audio" (using ac3, the same format of those avi).

Now, checking the file data in kmplayer, the comment said it was muxed with VirtualDubMod. So i tried to mux the same files on VD and it worked on the dvd!

Now, i don't mind using virtual dub but i cannot stop wondering why is it any different than my favorite software. Any clue?

[eumagga0x2a]

Could you please provide a short sample which works and a short sample which fails? Please use WeTransfer, Mega, Dropbox or Google Drive, if possible.